Stand-Alone Access System for Minimally Invasive Spinal Surgery

ABSTRACT

A retractor assembly for defining a working channel to a surgical site for conducting minimally invasive spinal surgery includes a plurality of relatively articulable components. Temporary interconnections are formed between adjacent sidewalls of the components to hold the components in a desired configuration, such as in a closed triangular form. The components are articulable relative to each other for adjusting the working channel or for performing surgical functions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/164,831, filed Dec. 7, 2005, the entire disclosure of whichis hereby expressly incorporated by reference.

FIELD OF THE INVENTION

The invention relates to access systems for conducting minimallyinvasive spinal surgery, as involving progressively dilating andretracting tissue for exposing a surgical site, and to surgical toolingand procedures associated with such access systems.

BACKGROUND OF THE INVENTION

Minimally invasive spinal surgery, which avoids long incisions andattendant muscle damage, blood loss, and scaring associated withconvention spinal surgery, is also credited with shortening recoveryperiods and reducing postoperative pain, while producing good long-termoutcomes. Access portals to surgical sites are formed by making shortincisions (e.g., less than two centimeters) followed by progressivelydilating and retracting intervening tissue. Traditional spinal surgicalprocedures such as spinal fusion, disc repair, and deformity correctionscan be performed through the access portals, which are also referred toas working channels.

Typically, a set of dilators is used to form the access portals,beginning with a guide wire or pin that is inserted through the smallincision and advanced until the wire contacts bone in the vicinity ofthe intended surgical site. Progressively larger tubular dilators areinserted over the guide wire or pin in sequence for stretching muscleand other intervening tissue. A circular retractor replaces the finaldilator for holding back the stretched muscle and maintaining a workingchannel that exposes the intended surgical site. A linkage assemblyattached to the surgical table can be used for holding the retractor inplace. Surgical tools are inserted through the working channel withinthe retractor to perform the desired operation. Generally, the surgicalsite can be viewed directly through the circular retractor. However, anendoscope can be inserted into the working channel to provide enlargedimaging from one or more local perspectives of the surgical site.

US Patent Application Publication 2005/0101985 to Hamada discloses atapered obturator for replacing the conventional series of dilators. Thetapered obturator spreads tissue, first by working its tapered nose todepth and then by temporarily pivoting hemispheric sections apart. Afterre-closing the hemispheric sections of the obturator, a working tube,which also has hollow hinged hemispheric sections, is inserted over theobturator to secure the dilation gains. The obturator is then re-openedto pivot apart the hollow hemispheric sections of the working tube,further spreading tissue near the surgical site. Lock pins hold thehemispheric sections of the working tube apart, while the obturator iswithdrawn to expose a working channel that expands in one dimensionapproaching the surgical site.

US Patent Application Publication 2004/0230100 to Shluzas discloses aretractor having a wrap-around skirt for similarly expanding a workingchannel approaching a surgical site. The retractor, while in a generallycylindrical configuration, is inserted over a dilator or dilatorassembly that initially reaches the surgical site. The dilator ordilator assembly is then removed to provide access for inserting ascissored expander, which unfurls the wrap-around skirt into a generallyconical form. The scissored expander is then removed to expose thesurgical site through the expanded retractor.

U.S. Pat. No. 6,206,826 to Matthews et al. discloses a retractor ringformed by concentric inner and outer walls that are partitioned intochannels or other openings for holding or guiding surgical tools andancillary instrumentation. Retractor blades attach by way of clips tothe outer wall of the ring. A circular sleeve fits within the inner wallof the ring to provide general surgical access. In between, thepartitioned channels of the ring receive ancillary instruments insupport of surgical operations. The ring functions as a surgicalorganizer for arranging surgical instruments within a small accessportal and for training surgeons otherwise unaccustomed to workingthrough small working channels to surgical sites.

Conventional retractors, the hinged retractor of Hamada, the wrap-aroundretractor of Shluzas, and the retractor ring assembly of Matthews et al.maintain fixed access portals to surgical sites. Adjustments to the sizeor shape of the portals require the participation of additionaldilators, obturators, or expanders, which block the working channeluntil the adjustments are complete. Any change to the size or shape ofthe portal entrance requires a different retractor or retractor ring.

Other minimally invasive access systems have evolved closer toconventional surgical retractor systems but on a smaller scale. Forexample, U.S. Pat. No. 5,944,658 to Koros et al. discloses a retractorand distractor system that mounts a set of retractor/distractor bladesfrom an adjustable frame. Two arms of a retractor frame suspend opposingretractor blades. A crossbar linkage between the two arms of theretractor frame includes a gear rack drive for adjusting the spacingbetween the retractor blades. Two arms of a distractor frame suspendopposing distractor blades at right angles to the two arms of theretractor frame. A similar crossbar linkage between the two arms of thedistractor frame adjusts the spacing between the distractor blades. Atilting structure is also provided for pivoting the retractor balestogether with their support arms about the remaining retractor frame.Despite the complexity of the frame-based system, the manipulation ofindividual blades is limited, while the entire system can be unwieldyfor use securing the small surgical portals required for conductingminimally invasive surgery.

SUMMARY OF THE INVENTION

My invention responds to a need for more flexibility in theconfiguration of minimally invasive working channels to surgical sites.Surgical demands vary widely between patients and procedures and can bedifficult to accommodate within fixed portals of limited size. Newretractor assemblies in accordance with my invention include retractorstructures that can be articulated with respect to one another so thatthe dimensions of the working channels are less constrained incomparison to those of conventional minimally invasive retractorsystems. In addition to retractor blades, the new retractor assembliescan include specialized surgical tools, such as dissectors.

One version of the invention as a retractor assembly for conductingminimally invasive surgery includes relatively articulable retractorwings configured around a hollow space for defining a working channel toa surgical site. Slots are formed in the retractor wings, and retractorinserts are received within the slots in positions around the workingchannel.

The retractor wings preferably include three retractor wings, and theretractor inserts preferably include three retractor inserts receivablewithin the slots of the retractor wings. The retractor inserts aregenerally arranged as retractor blades that extend beyond a length ofthe retractor wings along the working channel. However, the retractorinserts can also be arranged to perform specialized surgical functions.For example, individual retractor inserts can be arranged as or replacedby dissecting tools or other instruments or devices for performing suchfunctions as propagating light to the surgical site, imaging thesurgical site, or irrigating or aspirating the surgical site.

Each of the slots preferably has a transverse cross section forreceiving the retractor inserts having a similar transverse crosssection and has a length that extends parallel to the working channel.Preferably, the slots limit transverse motion of the retractor insertswith respect to the retractor wings while permitting unrestrictedlongitudinal motion of the retractor inserts with respect to theretractor wings along the lengths of the slots.

One end of at least one of the retractor inserts preferably includes anadaptor for attachment to a holder, which can be arranged as a handlefor manipulating the retractor insert or as a linkage for attaching theretractor insert to a surgical table. The handle can be oriented atvarious angles to the retractor inserts (e.g., straight, 30 degree, or45 degree angles). Preferably, all of the retractor inserts includeadaptors for inserting the retractor inserts into the slots or forwithdrawing the retractor inserts from the slots.

The retractor wings are preferably related by temporaryinterconnections. The preferred retractor wings have adjacent sidewalls,and the interconnections are formed between the adjacent sidewalls ofthe retractor wings. The adjacent sidewalls can include mating featuresfor interconnecting the retractor wings. For example, the adjacentsidewalls take the form of joints. Such joints can include mating maleand female features between the adjacent sidewalls of the retractorwings for holding the retractor wings in a predetermined configuration.In addition, the adjacent sidewalls can be at least partly formed bybeveled surfaces that abut each other to function as compression joints.

The joints preferably permit relative angular motion between theretractor wings about axes occupying a continuum of positions along theworking channel. However, the same joints can be arranged to constrainrelative axial motion between the retractor wings along the workingchannel. Compressive forces applied to the retractor wings hold thetemporary interconnections between the retractor wings together in theform of compression joints that constrain collapse of the retractorwings into the working channel.

Alternatively, the temporary interconnections between retractor wingscan take the form of connecting members such as one or more latches thatreleasably interconnect adjacent retractor wings. The one or moreconnecting members can also comprise one or more pins that extendthrough portions of adjacent retractor wings or one or more connectingmembers formed by end caps that engage portions of adjacent retractorwings. The connecting members can also include one or more cornerfittings that engage portions of adjacent retractor wings. The cornerfittings are located between the adjacent sidewalls along the length ofthe retractor wings.

The retractor wings can be arranged in a form that is expandable in adirection that enlarges the working channel. The preferred retractorinserts include a length that extends along the working channel and atransverse breadth that extends substantially tangent to the workingchannel. The slots of the retractor wings can be made expandable toreceive retractor inserts of enlarged breadth.

For example, the retractor wings can be made of relatively movable partsto enable the slots to expand to receive the retractor inserts ofenlarged breadth. Interlocks between the movable parts can be used tohold the slots in an expanded form independently of the enlargedretractor inserts. The slots can have a variable cross-sectional shapeto assume at least one dimension of the cross-sectional shape of theretractor inserts when the retractor inserts are inserted into theexpandable slots. Retractor wings that are made of a flexible materialcan also form the expandable slots.

Generally, the retractor wings form a closed shape surrounding theworking channel. The closed shape can approximate a polygon. Atriangular closed shape is most preferred among the closed shapesbecause of the inherent stability of the triangular form. At least oneof the retractor wings preferably includes a slot with substantiallystraight walls. The retractor wings with straight-walled slots can bemade of two interleaved parts for readily expanding or contracting thestraight-walled slots to receive different size retractor inserts.However, the retractor wings can also be fashioned as segments of a moreconventional cylindrical form having a substantially circular closedshape.

For performing surgical or retracting functions, one or more of theretractor inserts can extend beyond the retractor wings for more closelyapproaching or entering the surgical site. The specialized retractorinserts can have different lengths.

Another version of the invention as a retractor assembly for conductingminimally invasive surgery includes at least three retractor blades thatare relatively articulable with respect to each other and areconfigurable for defining a working channel to a surgical site. Each ofthe retractor blades has a length and inner and outer surfaces joined bytwo side surfaces. The retractor blades are configurable such that thelengths of the retractor blades align in a substantially commondirection along the working channel and the inner surfaces of theretractor blades face an interior of the working channel. The sidesurfaces between adjacent retractor blades are shaped for retaining theretractor blades in a desired configuration surrounding the workingchannel.

Preferably, the side surfaces of adjacent retractor blades are shaped toform temporary interconnections between the adjacent retractor blades.For example, the side surfaces of adjacent retractor blades can includemating features for temporarily interconnecting the adjacent retractorblades. The mating features can include male and female features formedin the side surfaces of adjacent retractor blades. One side surface ofeach of the retractor blades can include a male feature and the otherside surface of each of the retractor blades can include a femalefeature.

The adjacent retractor blades preferably contact each other through arange of positions along a common length of the adjacent retractorblades. The mating features of the adjacent retractor blades preferablyextend through the range of contact positions. In addition, the matingfeatures preferably remain substantially constant through the range ofcontact positions.

The side surfaces between adjacent retractor blades can take the form ofjoints, which can be shaped to permit relative angular motion betweenthe retractor blades over a continuum of positions along the lengths ofthe retractor blades or to permit relative translation between thecontacting portions of adjacent retractor blades. The joints arepreferably held together by compressive forces applied to the retractorsand prevent the collapse of the retractors into the working channel. Forexample, the side surfaces between adjacent retractor blades can beformed at least in part as mating bevel surfaces that abut each other tofunction as compression joints.

The retractor blades preferably include top and bottom ends and includean adaptor mounted adjacent to the top end of at least one the retractorblades. The adaptor can be used to attach a handle to the retractorblades or to participate in attaching the retractor blades to a surgicaltable.

One or more of the retractor blades can differ from other of theretractor blades. For example, the one retractor blade can be arrangedas a dissecting tool or as an instrument for propagating light to thesurgical site or for imaging the surgical site. One of the retractorblades can also be arranged for irrigating or aspirating the surgicalsite.

The individual retractor blades can be replaced for performing differentor revised functions. The preferred retractor blades are configurableinto closed shape surrounding the working channel. The closed shape canapproximate a polygon, but preferably approaches a triangle.

At least one and preferably both of the inner and outer surfaces of theretractor blades have sections that are substantially planar. The totalnumber of retractor blades is preferably limited to three retractorblades so that the retractor blades can be configured in a naturallystable form.

Another version of the invention as a dilator assembly for exposing asurgical site with minimal invasion includes a set of progressivelylarger dilators for opening a surgical site in stages. Each of thedilators includes an internal surface having an internal cross-sectionalshape and an external surface having an external cross-sectional shape.An interim one of the dilators has substantially rounded internal andexternal cross-sectional shapes. A transitional one of the dilators hasan internal surface with a rounded internal cross-sectional shape thatsubstantially matches the rounded external cross-sectional shape of theinterim dilator and has an external surface that includes a non-roundedexternal cross-sectional shape.

Preferably, the external surface of the transitional dilator transitionsfrom a rounded cross-sectional shape at one end to a non-roundedcross-sectional shape at an opposite end. The non-rounded externalcross-sectional shape of the transitional dilator is preferablyapproximately triangular, whereas the rounded internal cross-sectionalshape of the transitional dilator is preferably approximately circular.The dilator assembly also preferably includes a retractor assemblyhaving non-rounded internal and external cross-sectional shapes. The setof dilators are removable for exposing the surgical site through anon-rounded working channel bounded by the retractor assembly.

The retractor assembly preferably includes at least one relativelyarticulable retractor blade for manipulating the surgical site. Theretractor assembly can also include relatively articulable retractorwings within which slots are formed. The slots receive retractor insertswithin the retractor wings. At least one of the retractor insertsextends beyond the retractor wings toward the surgical site. Theretractor inserts can differ from one another for supporting two or moredifferent surgical functions.

The retractor wings are preferably interconnected by joints that permitrelative motion between the retractor wings while preserving a workingchannel to the surgical site. In addition, the retractor inserts arepreferably pivotable together with the retractor wings in directionsthat expand the working channel at the surgical site.

Alternatively, the retractor assembly can also be formed as anassemblage of three or more retractor blades that can be separatelymanipulated. The blades surround a working channel to the surgical site.Although all of the blades preferably participate in a tissue retractionfunction, the blades can differ from one another to perform additionalfunctions in support of a surgical operation. For example, theindividual blades can be arranged as a dissector, an illuminator, siteimager, irrigator, or aspirator. The blades can have different sizes andshapes for performing the different functions. Since the blades definethe working channel to the surgical site, the blades are not confinedwithin a fixed space and can be manipulated for adjusting the boundaryof the working channel.

Another version of the invention as a method of initiating a minimallyinvasive surgical procedure includes dilating tissue for forming aworking channel to a surgical site and supporting the working channelwith a retractor assembly having at least three relatively articulablecomponents that are positioned around the working channel with temporaryinterconnections bridging adjacent sidewalls of the components. Each ofthe relatively articulable components is pivotable with respect to theother of the relatively articulable components about a range ofdifferent pivot axes.

Preferably, the relatively articulable components have overlappinglengths and the different pivot axes are spaced apart between ends ofthe overlapping lengths. Each of the relatively articulable componentscan also be translated with respect to the other relatively articulablecomponents in a direction along the overlapping lengths of therelatively articulable components.

The relatively articulable components preferably include at least threeretractor wings that are configured around the working channel to thesurgical site. One or more retractor blades can be inserted through theretractor wings in positions that extend beyond the retractor wingstoward the surgical site. Each retractor blade together with theretractor wing in which the blade is inserted can be pivoted withrespect to other of the retractor wings for adjusting the workingchannel to the surgical site.

Alternatively, one or more dissecting tools can be inserted through theretractor wings in positions that extend beyond the retractor wingstoward the surgical site. Each of the dissecting tools can be pivotedtogether with the retractor wing in which the tool is inserted withrespect to other of the retractor wings for carrying out a dissectingfunction at the surgical site.

Initially, the slots within the retractor wings can be filled withtemporary plugs prior to the step of supporting the working channel withthe retractor assembly. The plugs can be replaced within the retractorwings with one or more surgical tools while the retractor wings are inplace around the working channel.

The relatively articulable components can also include a plurality ofretractor blades having the side surfaces between adjacent retractorblades that are shaped for retaining the retractor blades in a desiredconfiguration surrounding the working channel. Interconnections formedbetween the side surfaces of the retractor blades can be used to sustainthe retractor blades in a stable form surrounding the working channel.Preferably, each of the retractor blades can be both pivoted andtranslated with respect to other of the retractor blades.

Prior to inserting the retractor assembly, progressively larger dilatorscan be inserted one over the other for enlarging the working path to thesurgical site. Preferably, a transitional dilator having a roundedinternal cross sectional shape and a non-rounded externalcross-sectional shape is inserted over a smaller dilator having arounded internal and external cross-sectional shape. The retractorassembly can have a non-rounded internal cross-sectional shapeconforming to the non-rounded external cross sectional shape of thetransitional dilator and can be inserted over the transitional dilatorfor defining the working channel to the surgical site.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a perspective view of a retractor assembly configured from aset of retractor wings and having a handle attached to a retractorinsert received within one of the retractor wings.

FIG. 2 is a front view of the retractor assembly of FIG. 1.

FIG. 3 is a side view of the retractor assembly of FIG. 1.

FIG. 4 is a back view of the retractor assembly of FIG. 1.

FIG. 5 is a top view of the retractor assembly of FIG. 1.

FIG. 6 is a bottom view of the retractor assembly of FIG. 1.

FIG. 7 is a greatly enlarged cross-sectional view through a midsectionof the retractor assembly showing retractor inserts arranged for fillingslots through the retractor wings.

FIG. 8 is a partially enlarged perspective view of the retractorassembly of FIG. 1 showing one of the retractor wings separated from theremaining retractor wings.

FIG. 9 is a perspective view of another retractor assembly havingretractor inserts formed by elongated retractor blades.

FIG. 10 is a front view of the retractor assembly of FIG. 9.

FIG. 11 is a back view of the retractor assembly of FIG. 9.

FIG. 12 is a perspective view of a different retractor assembly fittedwith a retractor insert modified to function as an illuminator.

FIG. 13 is a front view of the retractor assembly of FIG. 12.

FIG. 14 is a bottom view of the retractor assembly of FIG. 12.

FIG. 15 is a front view of an alternative retractor insert modified tofunction as both an illuminator and an imager.

FIG. 16 is a front view of an alternative retractor insert modified tofunction as an irrigator or aspirator.

FIG. 17 depicts a dilator system having a set of dilators thatprogressively vary in both size and shape.

FIG. 18 is a top view of the set of dilators.

FIG. 19 is a greatly enlarged cross-sectional view of a set ofexpandable retractor wings holding retractor inserts of a first breadth.

FIG. 20 is a greatly enlarged cross-sectional view of the same set ofexpandable retractor wings in an expanded condition for holding aretractor insert of a larger breadth.

FIG. 21 is a front view of a pair of retractor wings temporarily heldtogether by a latch.

FIG. 22 is a greatly enlarged cross-sectional view of a retractorassembly showing corner fittings for temporarily holding the retractorwings together.

FIG. 23 is a back view of an alternative retractor assembly having anapproximately circular closed cross-sectional shape.

FIG. 24 is a cross-sectional view of the circular retractor assemblytaken along line 24-24 of FIG. 25 is a plan view of an operating tableshowing a frame for securing a set of retractor blades to the table.

FIG. 26 is a side view of the operating table and frame for securing theretractor blades.

FIG. 27 is a perspective view of a retractor assembly constructed by aset of three retractor blades in a triangular configuration.

FIG. 28 is a front view of the retractor assembly of FIG. 27.

FIG. 29 is an enlarged cross-sectional view of the retractor assemblytaken along line 29-29 of FIG. 28.

DETAILED DESCRIPTION OF THE INVENTION

A retractor assembly 10 intended for the practice of my invention isshown in FIGS. 1-6 from various perspectives. Three relativelyarticulable retractor wings 12A, 12B, and 12C are configured into atriangular shape appropriate for defining a working channel 15 to asurgical site. Each of the retractor wings 12A-C extends a lengthbetween top and bottom ends 14 and 16 and includes inner and outersurfaces 18 and 20, joined by opposite side surfaces 22 and 24. Fordefining the working channel 15, the retractor wings 12A-C areconfigured so that their lengths are aligned in a common direction alongthe working channel and their inside surfaces 18 face an interior of theworking channel 15. The retractor wings 12A-C are preferably made ofmetal or resin materials, such as polypropylene resin or stainlesssteel, aluminum, or titanium metals, that are safe for contact with bodytissues.

Slots 28A, 28B, and 28C, which have a generally rectangularcross-sectional shape, extend through the full lengths of the respectiveretractor wings 12A-C. Received within the respective slots 28A-C, areretractor inserts 30A, 30B, and 30C also having a generally rectangularcross-sectional shape for substantially filling the slots 28A-C.

The retractor inserts 30A-C can also be made of varioustissue-compatible materials, selected largely based on their intendedfunction. For example, as plugs that fill the slots 28A-C for performinga dilating function, the retractor inserts 30A-C can be made of resinmaterials. However, for performing more demanding surgical functions,such as dissection, the retractor inserts 30A-C are preferably made of asteel or strong polycarbonate material. Each of the retractor inserts30A-C has a slat-shaped body 32 and top and bottom ends 34 and 36. Thetop ends 34 of the retractor inserts 30A-C include shoulders 38 thatfunctions as stops against top ends 14 of the retractor wings 12A-C.Posts 40 and 42 project orthogonally from the shoulders 38. The posts 40project in a direction that extends along the length of the retractorinserts 16A-C and, in situ, also project in alignment with the lengthsof the slots 28A-C and the intended length of the working channel 15 tothe surgical site. The posts 42 project in a direction normal to thewide sides of the slat-shaped bodies 32 and, in situ, also projectnormal to the outer surfaces 20 of the retractor wings 12A-C andradially of the intended working channel 15.

The posts 40 together with the shoulders 38 provide adapters forattaching the retractor inserts 30A-C to another device such as a handle44 for individually manipulating the retractor inserts 30A-C or alinkage (not shown) for attaching the retractor inserts 30A-C to asurgical table. For example, the handle 44 is shown in a position forpartially inserting or partially retracting the retractor insert 30A toor from the retractor wing 12A. The handle 44 includes a bent shaft 45and a sleeve 46 that releasably engages the post 40 of the retractorinsert 30A. The shaft 45 can be bent at different angles, includingangles of 30 degrees or 45 degrees, or the shaft 45 can be straight asdesired to aid in the manipulation of the individual retractor inserts.The posts 42 also provide a ready grip for inserting or removing theretractor inserts 30A-C from their respective retractor wings 12A-C.

As shown in the enlarged cross-sectional view of FIG. 7, the retractorwings 12A-C are configurable in a stable triangular form for definingthe working channel 15 to the surgical site. The side surfaces 22 and 24have abutting beveled surfaces 48 and 50 that include male and femalemating features 52 and 54, which extend for all or just a part of thelength of the retractor wings 12A-C, for temporarily holding theretractor wings 12A-C in the desired triangular configuration.Variations in the male and female features 52 and 54 along the length ofthe retractor wings can prevent relative axial motion between theadjacent retractor wings, while the adjacent retractor wings are soengaged. Preferably, the male and female mating features 52 and 54 ofthe bevel surfaces 48 and 50 form compression joints that are drawntogether in situ by elastic tissue separated under the force ofdilation. The male and female features 52 and 54 are preferably formedin the opposite side surfaces 22 and 24 of each of the retractor wings12A-C so that all three retractor wings 12A-C have the same overallform. Although the mating features 52 and 54 are depicted as a type ofball and socket joint, a variety of other temporary joint structures canbe used including various forms of interlocks, detents, keepers,catches, and splines, or even simple frictional interfaces. The adjacentside surfaces 22 and 24 or the mating features 52 and 54 can be variedalong the lengths of the retractor wings 12A-C, such as by adopting aninterrupted, stepped, or serpentine form to prevent relative movementbetween the retractor wings 12A-C along their length.

The mating features 52 and 58 preferably function to hold the desiredtriangular configuration under conditions of asymmetric compression andprevent the collapse of the retractor wings 12A-C into the workingchannel 15. However, the mating feature 52 and 54 do not prevent theretractor wings 12A-C from being individually manipulated such as bybeing pivoted or otherwise drawn apart from the other retractor wings12A-C. For example, as shown in FIG. 8, the retractor wing 12A ispivoted apart from the retractor wings 12B and C for enlarging theworking channel 15 or for aiding or performing other surgically relatedfunctions. The handle 44 is coupled to the post 40 of the retractorinsert 30A and pivots the retractor wing 12A via the sliding fitconnection of the retractor insert 30A to the retractor wing 12A. Theretractor wing 12A or any other of the individual retractor wings 12B orC can be pivoted in other directions or otherwise separated from theother retractor wings to temporarily dilate the working channel 15 or tootherwise aid or perform surgical functions.

The retractor inserts 30A-C are sized largely as fillers for the slots28A-C within the retractor wings 12A-C for such purposes as preventingtissue from entering the ends 16 of the retractor wings 12A-C as a finalor intermediate dilator tool. The ends 36 of the retractor inserts 30A-Care tapered to preliminarily retract tissue during insertion and guidethe retractor wings 12A-C along the working channel 15 toward thesurgical site.

FIGS. 9-11 illustrate a modified retractor assembly 60 that includes anumber of similarly referenced features as the retractor assembly 10including the three retractor wings 12A-C and the handle 44. However,longer inserts referred to as retractor blades 70A, 70B, and 70C replacethe three retractor inserts 30A-C. Like the retractor inserts 30A-C,each of the retractor blades 70A-C has a slat-shaped body 72 and top andbottom ends 74 and 76. The top ends 74 of the retractor inserts 70A-Cinclude shoulders 78 that functions as stops against the top ends 14 ofthe retractor wings 12A-C. Posts 80 and 82 project orthogonally from theshoulders 78 as adapters or grips for manipulating the individualretractor blades 70A-C. For example the posts 80 are shown coupled tothe sleeve 46 of the handle 44. Either post 80 or 82 can be connected toa structure for manipulating the retractor wings 12A-C or to a linkagemechanism for securing the retractor wings 12A-C in place.

The retractor blades 70A-C have a length in the direction of the workingchannel 15 that exceeds the length of the retractor inserts 30A-C. Theends 76 of the retractor blades 70A-C are preferably formed as taperededges that can participate in the dilating function or in varioussurgical functions such as dissection. For example, the edges can beused to clean muscle from limited areas of bone within the surgicalsite.

FIGS. 12-14 depict a further modified the retractor assembly 90, whichis similar to the retractor assembly 60 except for the substitution of aretractor insert 100A for the retractor blade 70A to provide forilluminating the surgical site. The retractor insert 100A has aslat-shaped body 102 and top and bottom ends 104 and 106. The top end104 of the retractor inserts 100A includes a shoulder 108 that functionsas a stop against the top ends 14 of the retractor wings 12A-C.

In contrast to the earlier embodiments, a post 110 functions as anoptical input port for coupling a fiber optic or other light conduit tothe retractor insert 100A for connecting the retractor insert to asource of light. Within the slab-shaped body 102, an optical splitter(not shown) divides light coupled at the optical input port (post) 110into three optical pathways (not shown) that terminate at the bottom end106 of the retractor insert 100A with optical output ports 112, 114, and116. Fibers or other waveguides can form the optical pathways fortransmitting light from the optical input port (post) 110 to the opticaloutput ports 112, 114, and 116. Fiber ends, lenses, or other opticalstructures can form the optical output ports 112, 114, and 116 fordispersing light in a desired pattern at the surgical site.

A further modified retractor insert 120A is depicted in FIG. 15 forperforming an imaging function. In addition to the illuminating featuresdepicted for the retractor insert 100A, the retractor insert 120Aincorporates a video camera 122 that is connected by way of a cable 124to a video monitor or other device capable of significantly enlargingthe images captured by the video camera 122. The retractor insert 120Acan be manipulated both with respect to and together with a retractorwing, such as the wings 12A-C, for altering the position of the videocamera 122 at the surgical site. A zoom lens or other focusing orpositioning controls can be incorporated into the video camera 122 toremotely control its operation.

Another modified retractor insert 130A shown in FIG. 16 includes aninternal conduit 132 beginning at a top end 134 of the insert 130A witha connector port at a post 136 and ending at a bottom end 138 with anozzle or other opening 140. The conduit 132 can be used for purposes ofirrigation or aspiration of the surgical site. Separate conduits can beformed in the retractor insert 130A for separately supporting bothirrigation and aspiration functions.

A dilating system 150 is shown in FIGS. 17 and 18 of a type that canprovide the necessary dilation for inserting the above-describedretractor assemblies 10, 60, or 90 along a working channel to a surgicalsite. The system begins as usual with a fine wire or pin 152 that isinserted through a small incision to the surgical site. Progressivelylarger tubular dilators 154, 156, and 158 with tapered noses 160, 162,and 164 provide for gradually enlarging the working channel to thesurgical site.

The dilator 158, like the smaller tubular dilators 154 and 156, includesan internal surface 166 and an external surface 168, both having rounded(e.g., approximately circular) cross-sectional shapes. A transitionaldilator 170 has an internal surface 172 with a rounded (e.g.approximately circular) cross-sectional shape that substantially matchesthe rounded cross-sectional shape of the external surface 168 of thedilator 158 and has an external surface 174 that transitions from arounded cross-sectional shape near a tapered nose 176 to a non-rounded(e.g., substantially triangular) cross-sectional shape at an oppositeend 178. A retractor assembly 180, which is inserted over thetransitional dilator 170, includes an assembly of three retractor wings182A, 1828, and 182C that collectively form internal and externalsurfaces 184 and 186 that both exhibit a non-rounded (e.g.,substantially triangular) internal cross-sectional shape. The internalsurface 184 of the retractor assembly substantially matches thenon-rounded (e.g., substantially triangular) cross-sectional shape ofthe transitional dilator's external surface 174. Once so assembledthrough an incision to a surgical site, the dilator assembly includingdilators 152, 154, 156, 158, and 170 can be removed, leaving theretractor assembly 180 in place for exposing a triangular-shaped workingchannel to the surgical site.

The transitional dilator 170 can have a non-rounded external surfacethat extends for all or nearly all of its length. In addition, more thanone transitional dilators can be used to progressively vary in crosssectional shape from an initial rounded cross-sectional shape to anon-rounded cross-sectional shape matching the intended internalcross-sectional shape of a retractor assembly. Preferably, thenon-rounded cross-sectional shape approaches the form of a polygonhaving the same number of sides as retractor blades or wings that formthe retractor assembly. The corners of the polygonal cross-sectionalshapes, particularly the triangular external cross-sectional shapes, arepreferably radiused, chamfered, or otherwise blunted to avoidover-stressing surrounding tissue. Accordingly, the polygonalcross-sectional shapes can be recognized by the number of lobes found inthe external surfaces of the transitional dilators or the retractorassemblies.

The retractor wings 182A-C, like the retractor wings illustrated in thepreceding embodiments, have a fixed cross-sectional size and shape forreceiving retractor inserts having a similar cross-sectional size andshape. However, as shown in FIGS. 19 and 20, a retractor assembly 190can be configured with a set of retractor wings 192A, 192B, and 192Cthat are expandable in a direction that enlarges the working channel 15.

Each of the retractor wings 192A-C includes two relatively movable parts194 and 196 that are interconnected by an expandable joint 198 thatallows the relatively movable parts 194 and 196 to expand or contract toaccommodate different size retractor inserts 200A, 200B, and 200C or202A, 202B, or 202C. The expandable joints 198 can take a variety offorms, including interleaving overlaps, for allowing the expansion orcontraction of slots 204A, 204B, or 204C within the retractor wings192A-C. The different size inserts 200A-C or 202A-C can be used tosecure the retractor wings 192A-C in various expanded or contractedpositions, or the expandable joints 198 can incorporate interlocks, suchas catches, keepers, detents, pins, or frictional engagements so thatthe retractor wings 192A-C can hold their size independent of theretractor inserts 200A-C or 202A-C.

Whether expandable or not, the retractor wings can be temporarily heldtogether in a desired configuration in a variety of ways. For example,FIG. 21 depicts a latching mechanism 208 that can be used for securingadjacent retractor wings 210A and 210B. The latching mechanism 208,which includes a pivot bar 212 associated with the retractor wing 210Aand a catch 214 associated with the retractor wing 2108, is located neara top end 216 or the retractor wings 210A-B so as to be readilyaccessible for locking or unlocking the retractor wings 210A-B together.Other types of latching mechanisms can also be used, including bothintegral and non-integral structures that extend between adjacentretractor wings and provide releasable connections between the adjacentretractor wings. For example, pins, clasps, hasps, catches, bolts, endcaps, and other rigid fasteners can be used, as well as flexiblefasteners including elastic bands that encircle part or the entireperiphery of the retractor assemblies.

For example, FIG. 22 illustrates another way of temporarily holdingretractor wings together by using corner fittings 218 between adjacentpairs of retractor wings 220A, 220B, and 220C. Each of the cornerfittings 218 includes a main body 222 that abuts adjacent sidewalls 224and 226 of the retractor wings 220A-C and two ears 228 and 230 thatcontact interior surfaces 232 of the retractor wings 220A-C. The cornerfittings 218 secure the retractor wings 220A-C in a desired triangularconfiguration under compression while permitting the retractor wings220A-C to be individually pivoted or otherwise separated from theremaining retractor wings for performing individual operations.

An alternative retractor assembly 240 shown in FIGS. 23 and 24 includesin common with the preceding embodiments three retractor wings 242A,242B, and 242C and three retractor inserts 244A, 244B, and 244C but hasan overall circular rather than an overall triangular form. Each of theretractor wings 242A-C extends a length between top and bottom ends 246and 248 and has an inner surface 250 and an outer surface 252 joined bytwo side surfaces 254 and 256. The inner and outer surfaces 250 and 252have concentric arcuate shapes, and the side surfaces 254 and 256 ofadjacent retractor wings abut one another along radial lines. Althoughmating features can incorporated into the sides surfaces 254 and 256 forforming mechanical interlocks, the side surfaces 254 and 256 arearranged for a largely frictional engagement that is intended forretaining the retractor wings 242A-C in a circular closed form under theinfluence of anticipated asymmetric compression forces.

Arcuate slots 258A, 258B, and 258C are formed within the respectiveretractor wings 242A-C for receiving the retractor inserts 244A-C, whichalso have arcuate cross sections. The retractor insert 244A differs fromthe other two inserts 244B and 244C in both length and form forperforming a specialized surgical function, such as dissection. The slot258A allows the retractor insert 244A to be relatively translated alongthe length of the retractor wing 242A. The frictional interfaces formedby the abutting side surfaces 254 and 256 allow the retractor wing 242Atogether with the retractor insert 244A to be pivoted or otherwiseseparated from the adjacent retractor wings 242B and 242C for performingfunctions at or near the intended surgical site.

The retractor wings can be configured in a variety of overall closedforms for individually supporting retractor inserts having acorresponding variety of different cross-sectional shapes. Thecross-sectional shapes of the slots preferably remain constant along thelength of the retractor wings. Although the cross-sectional shapes ofthe retractor inserts preferably match the cross-sectional shapes of theretractor wing slots in which they are received, the cross-sectionalshapes of the retractor inserts can vary along their length,particularly at their working ends, to carry out their intendedfunctions.

The retractor inserts and with them the retractor wings can beindividually secured to a surgical table using conventional framingstructures. FIGS. 25 and 26 illustrate such a surgical setup. A post 260clamped to a side rail 262 of a surgical table 264 supports adjustablecrossbars 266 and 268 in positions cantilevered over a patient 270.Flexible, multilink connector arms 272, 274, and 276 can be manipulatedto connect individual retractor blades 278A, 278B, and 278C to thecrossbars 266 and 268. Once so connected, the links of the connectorarms can be tightened to provide a rigid connection to the crossbars 266and 268.

As shown in FIGS. 27-29, a set of three retractor blades 282A, 282B, and282C can be configured into a self-supporting retractor assembly 280 fordefining a working channel 284 to a surgical site. Each of the retractorblades 282A-C has a length between top and bottom ends 286 and 288 andinner and outer surfaces 290 and 292 joined by two side surfaces 294 and296. The retractor blades 282A-C are aligned in a common direction alongthe working channel 284 and their inner surfaces 290 face an interior ofthe working channel 284. At least the exposed surfaces of the retractorblades are preferably made of a tissue compatible material such asvarious metals or resins including polypropylene resin, stainless steel,aluminum, or titanium. The side surfaces 294 and 296 incorporate matingfeatures 298 and 300 for forming joints as temporary interlocks betweenadjacent retractor blades 282A-C.

Preferably, at least the female features 300 extend uninterrupted alonglengths of contact between the adjacent retractor blades 282A-C so thatthe retractor blades can be readily translated with respect to eachother along their respective lengths while maintaining a stableconfiguration or so that the retractor blades can be easily withdrawnand replaced with another retractor blade of the same or different size,shape, or function. The male features 298 also preferably extenduninterrupted along the lengths of the contact between the adjacentretractor blades 282A-C to allow the retractor blades 282A-C to be moresmoothly separated when pivoting or otherwise moving one of theretractor blades 282A-C out of engagement with its adjacent retractorblades. However, localized male features 298 can be used to favorcertain pivot positions over others between the adjacent retractorblades 282A-C.

The side surfaces 294 and 296 of the retractor blades 282A-C can beconfigured in a variety of other ways as shown for the retractor wingsof the preceding embodiments, including simple frictional engagementsand other types of temporary mechanical interlocks such as detents,keepers, catches, and splines. In addition, temporary connectors similarto those proposed between the retractor wings can be used between theadjacent retractor blades 282A-C including latches, pins, clasps, hasps,catches, bolts, elastic bands, end caps, and corner fittings.

Similar to the retractor inserts of the preceding embodiments, theretractor blades 282A-C include orthogonal posts 302 and 304 thatprovide adapters for attaching the retractor blades 282A-C to anotherdevice such as a handle for individually manipulating the retractorblades 282A-C or a linkage mechanism for attaching the retractor blades282A-C to a surgical table.

Although the retractor blades 282A-C have a substantially rectangularcross section, the retractor blades can have a variety of differentcross-sectional forms, especially such forms as may be desirable forperforming specialized surgical tasks such as dissection. The bottomends 288 of the retractor blades 282A-C can also be shaped according totheir intended use. All three of the retractor blades 282A-C can besubstantially similar, or the retractor blades can be individuallyvaried in structure, form, or length for accomplishing differentsurgical or surgical support functions in addition to retraction,including dissection, illumination, imaging, irrigating, or aspirating.

The retractor blades 282A-C can also be varied in number or form toadjust the shape or size of the working channel 284. When configuredtogether as intended, the retractor blades 282A-C complete a closedform, which is preferably triangular. However, the retractor bladeassemblies can assume a variety of different closed shapes includingpolygonal closed forms based on a plurality of retractor blades havingsubstantially straight inner surfaces or even more conventional circularforms based on a plurality of retractor blades having substantiallyarcuate inner surfaces.

Although the invention has been described with respect to a limitednumber of embodiments, modifications can be made to the variousembodiments and other embodiments will be suggested to those of skill inthe art in accordance with the overall teachings of the invention. Whilethe invention is particularly suitable for conducting minimally invasivespinal surgery, other minimally invasive surgeries could also benefitfrom these general teachings, particularly where increased flexibilityand functionality of retractor systems is needed.

What is claimed is:
 1. A retractor assembly for conducting minimallyinvasive surgery comprising at least three retractor blades that arerelatively articulable with respect to each other and are configurablein a closed shape for defining a working channel to a surgical site,each of the retractor blades having a length and inner and outersurfaces joined by two side surfaces, the retractor blades beingconfigurable such that the lengths of the retractor blades align in asubstantially common direction along the working channel and the innersurfaces of the retractor blades face an interior of the workingchannel, the side surfaces between adjacent retractor blades beingarranged to abut each other in the form of compression joints to retainthe retractor blades in a desired configuration surrounding the workingchannel and to constrain a collapse of the retractor blades into theworking channel, interconnections between the retractor blades beinglimited to the compression joints which are shaped to (a) permitrelative angular motion between the retractor blades toward and awayfrom the working channel over a continuum of positions along the lengthsof the retractor blades and (b) permit relative translation between theretractor blades in the substantially the common direction along theworking channel.
 2. The retractor assembly of claim 1 in which thejoints between adjacent retractor blades include mating features fortemporarily interconnecting the adjacent retractor blades.
 3. Theretractor assembly of claim 2 in which the mating features include maleand female features formed in the side surfaces of adjacent retractorblades.
 4. The retractor of claim 3 in which the mating feature of oneside surface of each of the retractor blades includes a male feature andthe mating feature of other side surface of each of the retractor bladesincludes a female feature.
 5. The retractor assembly of claim 3 in whichthe mating features remain substantially constant through the range ofcontact positions along a common length of the adjacent retractorblades.
 6. The retractor assembly of claim 1 in which joints between theside surfaces of adjacent retractor blades are formed at least in partas mating bevel surfaces.
 7. The retractor assembly of claim 1 in whichthe retractor blades include top and bottom ends, and further comprisingan adaptor mounted adjacent to the top end of at least one of theretractor blades and a handle is attached to the one retractor bladethrough the adaptor.
 8. The retractor assembly of claim 1 in which theone retractor blade is arranged as a dissecting tool.
 9. The retractorassembly of claim 8 in which another of the retractor blades differsfrom the one retractor blade for performing an additional surgicallyrelated function.
 10. The retractor assembly of claim 9 in which theanother retractor blade is arranged for at least one of propagatinglight to the surgical site and imaging the surgical site.
 11. Theretractor assembly of claim 9 in which the another retractor blade isarranged for at least one of irrigating and aspirating the surgicalsite.
 12. The retractor assembly of claim 1 in which additionalretractor blades are arranged for individually replacing one or more ofthe retractor blades performing a different or revised function.
 13. Theretractor assembly of claim 1 in which the closed shape approximates atriangle for holding a stable shape under compression from surroundingdilated tissue.
 14. A method of initiating a minimally invasive surgicalprocedure comprising steps of: inserting progressively larger dilatorsone over the other for dilating tissue and enlarging the working path tothe surgical site, wherein one of the dilators is a transitional dilatorhaving a rounded internal cross sectional shape and a non-roundedexternal cross-sectional shape over a smaller dilator having a roundedinternal and external cross-sectional shape, inserting a retractorassembly over one of the progressively larger dilators having anon-rounded external cross-sectional shape, wherein the retractorassembly has a non-rounded internal cross-sectional shape conforming atleast in part to the non-rounded external cross sectional shape of theprogressively larger dilator, supporting the working channel with aretractor assembly having at least three relatively articulableretractor components that are positioned around the working channel,abutting sidewalls of adjacent retractor components to form compressionjoints to retain the retractor components of the retractor assembly in aclosed form surrounding the working channel, and limitinginterconnections between the retractor components for constraining thecollapse of the retractor components into the working channel to thecompression joints.
 15. The method of claim 14 further comprising stepsof relatively pivoting at least one of the retractor components withrespect to the other retractor components toward and away from theworking channel and restoring the retractor assembly to the closed form.16. The method of claim 14 further comprising steps of relativelytranslating at least one of the retractor components with respect to theother retractor components in a direction along the working channel andrestoring the retractor assembly to the closed form.
 17. The method ofclaim 14 in which the joints between adjacent retractor componentsinclude mating male and female features formed in the sidewalls ofadjacent retractor components.
 18. The method of claim 14 furthercomprising steps of providing a plurality of interchangeable retractorcomponents and replacing one of the retractor components of theretractor assembly with one of the interchangeable retractor componentsfor performing a different or revised surgical function.
 19. The methodof claim 18 in which at least one of the retractor components of theretractor assembly is a dissecting tool.
 20. The method of claim 14 inwhich the closed form of the retractor assembly is a triangle forholding a stable shape under compression from the surrounding dilatedtissue.